Printed electronics gathering pace

Printed electronics has moved rapidly from lab to manufacturing processes in recent years

By Morand Fachot

Printed electronics is a relatively new technology, but it has already proven a disruptive, yet creative process that allows the production of new products and components, low-cost electronic devices, which open the way to a range of new applications. It has started transforming the electronics industry and many other domains by being included in different manufacturing processes. This new technology led to the creation, in 2011, of IEC Technical Committee (TC) 119: Printed electronics.

ultra-thin, flexible battery from Imprint Energy Imprint Energy has developed an ultra-thin, energy-dense, flexible, and low cost rechargeable battery, suing zinc instead of lithium-ion (Photo: Imprint Energy)

Designation may be misleading

The production of printed circuit boards (PCBs), used in computers, TV or radio sets and many other electronic products and parts, launched decades ago, may give the impression that “printed electronics” (PE) has been around for a long time, actually PE is a “new kid on the block”. It consists in the creation of electronic devices and components using various printing methods, equipment and material such as special substrates, conductive and dielectric inks. PE makes possible the production of a wide variety of products increasingly found everywhere.

It has other advantages, such as a much lower production costs than conventional electronics and it can be applied to flexible or rigid supports (or substrates).

Countless products and applications

PE is already widely used in the production of radio frequency identification (RFID) tags placed on product packaging to protect against shoplifting, to help manage and track stocks, check shelf life, or to identify items, including luggage, during transport. RFID can also be built in contactless payment devices and even implanted into people. Some 14 billion RFID tags will be sold in 2017, up 40% on 2016, a market worth USD 11,2 billion, according to emerging technology research company IDTechEx.

PE is also used in the production of sensors, flexible electronic circuits which are widespread in products where space constraints are significant, such as in small consumer electronics devices, e.g. digital cameras, mobile phones.

It is now being introduced into the further development of photovoltaic (PV) devices and of wearable smart devices (WSDs) for use in a wide range of domains from leisure to wellness, health and medicine.

Furthermore, new printed electronics applications are emerging, opening up possibilities not envisaged before. One such application is in the domain of printed batteries. More than three years ago, US scientists printed a lithium-ion battery the size of a grain of sand that could one day power tiny medical implants as well as other microelectronic devices.

IDTechEx describes PE as “one of the fastest growing technologies in the world. It is of vital interest to industries as diverse as consumer goods, healthcare, mobility, electronics, media and architecture.”

From research to industrial design and marketable products

New technologies in the PE domain are emerging all the time and the market is fast expanding. IDTechEx estimates that the total market for PE and flexible PE worth some USD 7,6 billion in 2017 will exceed USD 46 billion in 2027.

PE is found in more and more mass-produced items, in particular in the automotive, consumer electronics and pharmaceutical industries.

The printed electronics industry currently covers five main areas:

  • Lighting, including both organic LED (OLED) and electroluminescent (EL) products
  • Organic photovoltaics (PV)
  • Flexible displays
  • Electronics and components, including RFID, memories, sensors, batteries and other components
  • Integrated smart systems (ISS) that include smart objects, sensors like microelectromechanical system (MEMS) and smart textiles

These areas that see widespread use of PE are already covered by several IEC TCs. This led TC 119 to embark upon a series of liaisons with other TCs and external organizations.

A good example of this is the liaison with IEC TC 47: Semiconductor devices, since many of the resultant products will be hybrid devices, with both printed and conventional silicon-based components being integrated into one unit. Similarly, the liaison with IEC TC 110: Electronic display devices, makes sense as components for electronic displays are already being produced by printing, and printable materials for OLED displays are commercially available. Most OLED displays are currently produced on rigid substrates, but flexible substrates will be used more widely in future OLED displays.

PE support for PV

Traditional silicon-based PV needs some physical protection from the weather when mounted on the outside of a building. This is most commonly achieved by assembling the active layers between two sheets of rigid material, which act as a physical barrier, preventing damage to the electrically-active assemblies.

As PV move away from rigid to flexible material, they can be printed on flexible substrates, which need to be protected by a multilayer barrier film glued or deposited onto the printed PV layer to be protected. This allows new design freedoms and it is anticipated that this will become an increasingly important market sector.

Sensors everywhere

Sensors are found in a growing number of devices and applications and demand is set to explode with the expansion of the devices needed by the internet of things (IoT) in home (smart homes) and wider environments (smart cities and industry).

PE offers countless and unparalleled opportunities to produce new types of sensors through miniaturization, reduction in power consumption and new form factors (flexibility). These sensors can be deployed in IoT, wearable smart devices (WSDs), consumer electronics and robotic application. Printed and flexible sensors currently represent a market worth some USD 6,1 billion. The market for environmental (air quality sensors) gas sensors (fixed outdoor/portable/indoor) will grow exponentially from less than USD 500 million in 2017 to some USD 3 billion in 2027, according to IDTechEx research.

WSDs major PE driver and beneficiary

WSDs are a category of products of high interest to PE. This is a field that provides a very good illustration of a systems integration challenge that requires input from a substantial number of horizontal technologies.

WSDs can be categorized in a variety of classes, such as “in body”, “on body” and “near body”. Of particular interest to the field of printed electronics are flexible electronic components. One example of these would be electronics printed onto textile substrates that are flexible and/or stretchable, giving rise to flexible displays integrated into garments. These could then be integrated into conformable wearable devices that could fit into everyday life in a variety of implementations.

The IEC Standardization Management Board (SMB) has recognized the potential of WSDs and the wide number of IEC TCs that have stakes in the applicable technologies. It started a Strategy Group, SG 10: Wearable smart devices, tasked with reporting back on strategy options for standardization. Following the SG 10 report the SMB created TC 124: Wearable electronic devices and technologies. This TC is set to liaise with a number of IEC TCs including, among others, TC 47, TC 62: Electrical equipment in medical practice, TC 100: Audio, video and multimedia systems and equipment, TC 119, TC 77: Electromagnetic compatibility, TC 106: Methods for the assessment of electric, magnetic and electromagnetic fields associated with human exposure, TC 108: Safety of electronic equipment within the field of audio/video, information technology and communication technology, and TC 111: Environmental standardization for electrical and electronic products and systems.

The health and safety aspect is of particular importance as the products will by definition be in close proximity to a human or animal. The substrates and functional materials employed must therefore of necessity be non-toxic and bio-compatible. As smart devices, they are likely to include some mode of wireless connection, so electromagnetic compatibility and safety are also important. This highlights some of the complex issues around systems integration, emphasizing the need for involvement of the multiple disciplines found in IEC TCs.

3D printing of electronic products

3D printing of electronic products shares many technologies with PE. Many electronic products are now printed, even making possible the fast prototyping of entire PCBs using inkjet technology, and nanoparticle inks. Advanced PCBs can be printed quickly and tested by manufacturers after design without having to call on third party companies to produce prototypes.

It is now possible also to add electronics on plastics to produce flexible and adaptable products using an additive metallization process for plastics and composite materials, which adds value on composite materials, especially in the automotive area.

Bright prospect on the horizon

TC 119 Chair Alan Hodgson notes that PE is fast closing the gap between lab and fab (laboratory project to industrial fabrication), PE is now ready for manufacture and integration with other technologies within the IEC family.

PE technologies will make it possible to produce many more products, more cheaply and more reliably in coming decades as the range of PE expands. Many of these products will rely on IEC International Standards developed by IEC TCs that will work and liaise closely with TC 119.

RFID tag RFID tags can be placed on product packaging to manage and track stocks, protect from shoplifting or identify items such as luggage (Photo: Metalcraft)
ultra-thin, flexible battery from Imprint Energy Imprint Energy has developed an ultra-thin, energy-dense, flexible, and low cost rechargeable battery, suing zinc instead of lithium-ion (Photo: Imprint Energy)
Smart skin patch listens to body sounds An electronic tattoo picks up sounds made by the heart, gastrointestinal tract or muscles for example (Photo: Jeong Lab, University of Colorado Boulder)
inkjet printed PCB A single-sided wiring pattern for an Arduino micro controller was printed on a transparent sheet of coated PET film (Photo: Georgia Institute of Technology)